基于tinyxml2实现的超轻量级参数获取工具（C++）

【前言】

ROS用习惯的朋友，当工程环境需要脱离ROS时，想必都会遇到很多的不适应吧。首当其冲的应该就是参数获取，之前可以通过ROS提供的参数服务器，launch文件之类的，轻松获取配置文件中的参数，但是脱离ROS了以后，这就成为了一个痛点。本篇博客就介绍一个我自己手写的XML参数获取工具！

 

【干货】

话不多说，直接上代码！

首先是头文件：

#ifndef XML_PARSER_H
#define XML_PARSER_H

#include "tinyxml2.h"
#include 

using namespace tinyxml2;

namespace util_data
{

class SimpleParam
{
public:
  SimpleParam();
  ~SimpleParam();
  bool loadXML(const std::string xml_path);
  bool getParam(const std::string name, std::string &value);
  bool getParam(const std::string name, int &value);
  bool getParam(const std::string name, double &value);
  bool getParam(const std::string name, float &value);
  bool getParam(const std::string name, bool &value);

public:
  XMLDocument doc;
};

}

#endif

其次是源文件：

#include "xml_parser/xml_parser.h"
#include 

using namespace util_data;

SimpleParam::SimpleParam()
{}

SimpleParam::~SimpleParam()
{}

bool SimpleParam::loadXML(const std::string xml_path)
{
  if(doc.LoadFile(xml_path.c_str()) != 0)
  {
    printf( "load xml file failed \n" );
    return false;
  }
  else {
    return true;
  }
}

bool SimpleParam::getParam(const std::string name, std::string &value)
{
  XMLElement *config = doc.RootElement();
  XMLElement *param = config->FirstChildElement("param");
  while (param)
  {
    const XMLAttribute *attributeOfSurface = param->FirstAttribute();
//    std::cout << attributeOfSurface->Name() << ":" << attributeOfSurface->Value() << std::endl;
    if(name == attributeOfSurface->Value())
    {
      value = attributeOfSurface->Next()->Next()->Value();
      return true;
    }
//    while(surfaceChild)
//    {
//      content = surfaceChild->GetText();
//      surfaceChild = surfaceChild->NextSiblingElement();
//      cout << content << endl;
//    }
    param = param->NextSiblingElement();
  }
  return false;
}

bool SimpleParam::getParam(const std::string name, int &value)
{
  XMLElement *config = doc.RootElement();
  XMLElement *param = config->FirstChildElement("param");
  std::string value_str;
  while (param)
  {
    const XMLAttribute *attributeOfSurface = param->FirstAttribute();
    if(name == attributeOfSurface->Value())
    {
      value_str = attributeOfSurface->Next()->Next()->Value();
      value = atoi(value_str.c_str());
      return true;
    }

    param = param->NextSiblingElement();
  }
  return false;
}

bool SimpleParam::getParam(const std::string name, double &value)
{
  XMLElement *config = doc.RootElement();
  XMLElement *param = config->FirstChildElement("param");
  std::string value_str;
  while (param)
  {
    const XMLAttribute *attributeOfSurface = param->FirstAttribute();
    if(name == attributeOfSurface->Value())
    {
      value_str = attributeOfSurface->Next()->Next()->Value();
      value = atof(value_str.c_str());
      return true;
    }

    param = param->NextSiblingElement();
  }
  return false;
}

bool SimpleParam::getParam(const std::string name, float &value)
{
  XMLElement *config = doc.RootElement();
  XMLElement *param = config->FirstChildElement("param");
  std::string value_str;
  while (param)
  {
    const XMLAttribute *attributeOfSurface = param->FirstAttribute();
    if(name == attributeOfSurface->Value())
    {
      value_str = attributeOfSurface->Next()->Next()->Value();
      value = std::stof(value_str.c_str());
      return true;
    }

    param = param->NextSiblingElement();
  }
  return false;
}

bool SimpleParam::getParam(const std::string name, bool &value)
{
  XMLElement *config = doc.RootElement();
  XMLElement *param = config->FirstChildElement("param");
  std::string value_str;
  while (param)
  {
    const XMLAttribute *attributeOfSurface = param->FirstAttribute();
    if(name == attributeOfSurface->Value())
    {
      value_str = attributeOfSurface->Next()->Next()->Value();
      if(value_str == "true")
      {
        value = true;
      }
      else {
        value = false;
      }
      return true;
    }

    param = param->NextSiblingElement();
  }
  return false;
}

再来一个测试代码：

#include 
#include "xml_parser/xml_parser.h"

using namespace std;

void example()
{
  XMLDocument doc;
  if(doc.LoadFile("/home/starlab/Box/test_ws/src/common/xml_parser/config/demo.xml")!=0)
  {
    cout << "load xml file failed" << endl;
    return;
  }

  XMLElement *scene = doc.RootElement();
  XMLElement *surface = scene->FirstChildElement("node");
  while (surface)
  {
    XMLElement *surfaceChild = surface->FirstChildElement();
    const char* content;
    const XMLAttribute *attributeOfSurface = surface->FirstAttribute();
    cout << attributeOfSurface->Name() << ":" << attributeOfSurface->Value() << endl;
    while(surfaceChild)
    {
      content = surfaceChild->GetText();
      surfaceChild = surfaceChild->NextSiblingElement();
      cout << content << endl;
    }
    surface = surface->NextSiblingElement();
  }
}

void example2()
{
  util_data::SimpleParam tool;
  std::string map_file;
  int nFeatures;
  double scaleFactor;
  bool load_map;
  if(tool.loadXML("/home/starlab/Box/test_ws/src/common/xml_parser/config/test_config.xml"))
  {
    tool.getParam("map_file", map_file);
    std::cout << map_file << std::endl;
    tool.getParam("/ORBextractor/nFeatures", nFeatures);
    std::cout << nFeatures << std::endl;
    tool.getParam("/ORBextractor/scaleFactor", scaleFactor);
    std::cout << scaleFactor << std::endl;
    tool.getParam("load_map", load_map);
    std::cout << load_map << std::endl;
  }
}

int main()
{
  example2();
  return 0;
}

【后言】

如果这篇博客对你起到了一定的帮助作用，还请点个赞！！